Tension regulator for stretch core thread



Jan. 13, 1970 E. A. REHWALD TENSION REGULATOR FOR STRETCH CORE THREAD 2 Sheefs-Sheet 1 Filed Oct. 17, 1967 I Wyn/r02 [1071/1/11 FzlwQ Jan. 13, 1970 E. A. RE'HWALD 3,

TENSION REGULATOR FOR STRETCH CORE THREAD Filed Oct. 1.7, 1967 2 Sheets-Sheet 2 INVENTOR.

E Mme/11a A. fieha/a/a BY [00% ZMw-J doll A TTOR/VEYS United States Patent O 3,489,368 TENSION REGULATOR FOR STRETCH CORE THREAD Edmund A. Rehwald, Rockford, Ill., assignor to Barber- Colman Company, Rockford, Ill., a corporation of Illinois Continuation-impart of application Ser. No. 530,122, Feb. 25, 1966. This application Oct. 17, 1967, Ser. No. 693,035

Int. Cl. B65h 59/18; D02j 1/22; D02g 3/36 U.S. Cl. 242--147 12 Claims ABSTRACT OF THE DISCLOSURE During the formation of a stretch core or so-called Spandex thread, the stretchable core thread is led from a supply mass through a guide eye to and reversely around one guide to a roller on which a continuous drag is exerted by a variably energizable eddy current brake. After extending more than a revolution around this roller, the thread extends back to and is led reversely around a second guide, then back to the roller and finally around the guide to the tensioning rolls. The multiple guide surfaces are the bottoms of fixed notches in a block or the bottoms of grooves in a rotary roller paralleling the drag roller.

CROSS-REFERENCE TO RELATED APPLICATION The application is a continuation-in-part of my pending application Ser. No. 530,122, filed Feb. 25, 1966, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to a device adapted to be interposed in the path of travel of so-called Spandex or other readily stretchable and resilient thread and operable automatically to maintain a uniform stretched condition thereof during winding of the thread onto a bobbin or the like. The invention has more particular reference to a tension regulator of the type in which the traveling and stretched thread is wrapped around a rotatable roll continuously subjected to a torque whose magnitude determines the amount of the stretching of the thread in the course of spinning.

SUMMARY OF THE INVENTION The general object is to provide a new and improved tension regulator of the above character which, as compared to prior devices, is more reliable in its regulating action, adjustable over a wider tension range, and sus ceptible of adjustment from a remote point.

For this purpose, the traveling thread is extended back and forth and around laterally spaced fixed guides and a drag roller around which the thread is wrapped one or more times each through substantially more than one revolution. Turning of the roller is resisted by a magnetically actuated and selectively controllable eddy current brake. For use with relatively coarse thread, the arcuate surfaces on the guides around which the thread is bent reversely are preferably stationary. For fine 3,489,368 Patented Jan. 13, 1970 lCC BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a fragmentary vertical sectional view of a conventional spinning frame for forming stretch core thread tensioned with a regulator embodying the novel features of the present invention.

FIG. 2 is a fragmentary section taken along the line 22 of FIG. 1.

FIG. 3 is a fragmentary perspective view of the improved tension regulator.

FIG. 4 is a fragmentary section taken along the line 4-4 of FIG. 3.

FIG. 5 is a fragmentary perspective rear view of the roller shown in FIG. 3.

FIG. 6 is a fragmentary perspective view similar to FIG. 3 showing a modification.

FIG. 7 is a perspective view similar to FIG. 3 showing a modified form of thread guide.

FIG. 8 is a section taken along the line 88 of FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the forms shown in the drawings, the invention is utilized to effect substantial but uniform stretching of a resilient thread 10 which constitutes the core of a composite thread including two elongated strands 11 and 12 of roving spun and wound onto a bobbin 13 to form a mass 14 of stretch core thread during rotation of an upright spindle 15 and the accompanying action of a conventional traveler ring 16 to which the three threads are led from a guide eye 17. In accordance with conventional spinning practice, the fibers of roving threads 11 and 12 are drawn off from packages 11 and 12 and elongated in passing through a series of drafting rolls 18, the final formation of the threads being effected by the twisting action of the traveler as the composite thread is wound onto the bobbin.

The core of the composite stretch core thread is composed of an elastomer such as polyurethane or so-called Spandex thread and is capable of being elongated without rupture, for example, up to or even more than six times its relaxed length and to return substantially to such length when not under tension. The terms stretch thread as used in the specification and appended claims refers to a thread having such properties. The supply of Spandex or stretch thread is a tubular package 20 telescoped onto an upright post 21 on a shelf 22 of the spinning frame. The thread is usually unwound endwise and upwardly off from the package through guide eyes 23 from which it is drawn downwardly between the lower pair 24 of the drafting rolls which grip the thread and advance it downwardly at a uniform velocity and without slipping.

A substantial distance above the rolls 24, the thread is gripped and a drag is applied thereto of sufficient magnitude to cause the intervening length to be elongated several, for example six, times its length when relaxed While maintaining the stretched thread under precisely uniform tension even though the thread adjacent the package is under light and variable tension and may at times be relatively slack due to the erratic manner in which the thread breaks away from the package proper. This is accomplished in accordance with the present invention by a device including a stationary guide 26 in FIG. 3 and 26' in FIG. 7 by which the thread as unwound from the package is led to a roller 27 and around the latter one -or more times each through substantially more than a revolution so as to provide adequate gripping of the roller for turning the latter against a resisting torque preferably produced by magnetic action.

Preferably the roller comprises a sleeve 28 having a cylindrical surface composed of an elastomer such as relatively firm rubber or polyurethane having a surface of a relatively high coefiicient of friction. The roller is fixed to a hub 29 which in turn is fast on the outer end of the shaft 30 journaled in spaced bearings 31 on a frame 32 which, through a bracket 33 is fixed to a shelf on the spinning frame. Herein, the drag on the roller is produced by an eddy current brake 34 housed within a box-like casing 19 secured to the frame 32. The brake is formed in the present instance by a conductive rotor 35 fast on the inner end of the shaft 30 so as to turn in a magnetic field permeating the space between opposite poles 36 at the ends of a magnet core 37. The latter is enclosed by a multiple turn winding 38 energized continuously from a direct current source (not shown). During turning of the roller and rotor, eddy currents are induced in its periphery thus causing a frictionless torque to be exerted on the roller. The efficiency of the eddy current brake is improved by employing a rotor of the squirrel cage type having bars 39 of copper or the like embedded in the iron cylinder and spanning end disks 40.

Since the magnitude of the generated eddy currents is proportional to the speed of the rotor, it is desirable to reduce the size of the roller 27 as much as possible without danger of slipping while maintaining the required length of thread gripping the roller. Accordingly, with a rotor one inch in diameter, an adequate drag may be obtained by a roller, three fourths of an inch in diameter and a surface composed of yieldable plastic material having a Shore durometer hardness of about 55.

In the form shown in FIGS. 1 to 6, the guide 26 is a bar of ceramic or the like paralleling and spaced from the roller 27 and having spaced notches 41, 42, 43 opening away from the roller while lying in transaxial planes thereof. A screw 44 projecting through a hole in the bar and threading into the magnet frame clamps one end of the latter against a spacer and the magnet casing 19.

In accordance with the present invention, the gripping between the thread and the roller to achieve the desired and substantial stretching of the thread 10 approaching is achieved by increasing the length of thread which engages the roller surface to substantially more than a single revolution, for example 540 degrees as illustrated. To this end, the relatively slack thread, as unwound from the package 20, is led downwardly into the first notch 41 in the guide bar 26, reversely around the arcuate bottom thereof and then at a to the roller and across the underside thereof. Then, the thread is wrapped upwardly and reversely around the roller at b for more than a full revolution and finally over the top of the roller at c and into the second notch 42 of the guide bar, the total wrap around the roller being about 540 degrees.

The invention also contemplates a further and substantial increase in the gripping of the roller, where greater stretching and higher tensions are desired, by snubbing the thread beyond the first multiple wrap 45 around the guide bar at the bottom of the notch 42 and providing a second multiple wrap 46 around the roller axially spaced from the first wrap. This is accomplished by leading the thread after the first wrap around the roller downwardly through the second notch 42 and reversely at d around the bottom of the roller. As before, the thread is led first upwardly and then around the roller at e and finally off from the top of the roller at f and downwardly through the notch 43 in the bar and to the draft rolls 24. Thus, in addition to the increased gripping of the roller by doubling the multiple wraps, the resistance to the advance of the thread is further increased by the snubbing around the bottoms of the notches in the guide bar 42 and 43.

If desired, the gripping of the thread around the roller 27 may be increased still further by increasing the lengths of the Wraps 45, 46. For this purpose, the thread, after passing around the bottom of the first notch 41 may be led upwardly and over the top of the roller, around the latter through one and one-half turns, off from the bottom of the roller and finally upwardly over the bar 26 and down through and around the bottom of the second notch 42. Of course, the two wraps 45 and 46 always extend in the same direction around the roller.

With a thread wrapped more than a revolution around the cylindrical surface of the roller 27 and running onto and off from the latter while under substantial tension, adjacent lengths ofthe wrap contact each other and become overlapped as illustrated at 48 and 49 in FIG. 5, a condition of tangling and snagging which would seem to be conducive to wide variations in the stretching tension produced as well as frequent breaking of the thread under the pull exerted by the draft rolls. I have discovered that these difficulties are avoided by virtue of the extremely stretchable character of the thread. Thus, I have found that when such overlapping of the adjacent turns occurs, an increased tension is developed in the leading part of the turn thus decreasing the diameter of the thread sufficiently in the area of the overlap to break the thread loose and cause it to crawl out from beneath the top turn. By taking advantage of this unexpected action, each condition of overlap is corrected automatically, and it is possible to maintain an extremely uniform tension in the thread as delivered to the drafting rolls while avoiding rupturing of the thread as the turning of the roller continues. Thus, the long length of gripping between the thread and the roller 27 necessary to produce the desired stretching and tensioning is obtained in spite of the small diameter of the roller which is desirable in order to produce the speed for inducing the desired eddy current drag.

In the unwinding of the thread from the package, substantial variations in tension may occur at times depending on how the thread breaks away from the main mass of the package 20 and, under certain conditions, the thread may become snagged on the package so that when it breaks loose, there may be a sudden slackening of the thread, beyond the guide eye 23 in this instance as indicated at 49 As a result, the thread is apt to lose its full contact with the roller 27. To prevent this, it may be desirable in some instances to provide means to apply a friction force to the thread between the package 20 and the guide 26 and of suflicient magnitude to prevent the propagation of such slack past the guide and to the turns on the roller. This means may take various forms such as a simple leaf spring pressing the thread against the surface of the guide bar 26 or a pair of spring fingers gripping the thread between them. Preferably, the necessary friction force is derived from the laterally flexible and resilient bristles 50 of a relatively short brush 51 mounted cantilever fashion with the free end of the bristles disposed in the path of travel of the thread to the guide. In the form shown in FIGS. 3 and 4, a ferrule 52 gripping the bristles at the other end of the brush is fixed to one end of an arm 53 clamped between the casing 19 and the end of the guide bar. The bristles are thus pressed against the top of the bar across the notch 41 and are thus positioned to receive and grip the thread as the latter is drawn into the notch in threading up the tension regulator.

As an alternative and as shown in FIG. 6, a similar brush 54 projecting from an arm 55 may be secured to the casing 19 with the free ends of the bristles spaced above the guide bar 26 at the notch 41 and lying in the path of the thread as it is laid initially into this notch. The thread thus enters between the bristles and, by virtue of the resiliency of the latter, is lightly gripped by a large number of the bristles which thus exert the necessary friction to prevent the thread from running ahead of the guide whenever the thread becomes snagged at the package and tends to snap ahead when it breaks loose.

It will be seen that each of the members 51 or 54 acts as a guide for leading the thread from the package 20 to the guide 26 While applying enough force to prevent objectionable slackening of the thread as it breaks away from the package. Thus, this form of guide supplements the action of the eyes 23 and may be substituted for the latter in some instances.

By extending the traveling thread back and forth a plurality of times between the guide26 and the drag roller 27, the desired tensioningwill be developed in successive steps. That is to say, the lengths a, c, d and f (FIG. 3) are tensioned to successively increasing degrees. Such action augmented by the snubbing of the thread around the successive guide surfaces provides the desired final tension which is maintained uniformly and of the desired magnitude determined by the degree of energization of the eddy current brake.

The improved tension regulator in the form above described is particularly adapted for use with relatively coarse thread, for example 800 denier, which will slide around the guide surfaces without danger of breaking. In the case of finer threads, for example 30 to 70 denier, this sliding friction may be reduced by using as the guides the bottoms of grooves 60 axially spaced along a roll 61 similar to the spacing of the notches 41-43 above described. This roll is journaled on the stud 44 to turn freely thereon, the tensioning of the thread thus being controlled by the drag applied by the thread wrapped around the roller 27 and also as a result of the slippage due to the different speeds of the thread input and output as it stretches. The roll 61 is preferably composed of plastic material such as Teflon, polypropylene or the like.

With the tension regulator constructed as above described the tensioning action remains unaffected by the changing conditions of unwinding at the package 20 or of overlapping of the adjacent turns of the multiple wraps 45 and 46. It has been found that the desired drag for producing the desired uniform stretch in the thread approaching the rolls 24 may be achieved with an input to the magnet winding of only five or six watts. At the same time, by varying the energization of the winding from a central station or through the individual rheostat 57 (FIG. 2) the tension may be varied as desired over an extremely wide range, for example, 12 to 150 grams, thus producing varying degrees of stress as required in stretch core threads for different uses.

I claim as my invention:

1. In mechanism for handling a stretchable thread having a guide member across which the thread is led from a supply package, power driven rolls engageable with the unwound thread at a point beyond and spaced from said guide member and exerting a continuous pull for continuously unwinding thread from the package, and mechanism engageable with the thread between said rolls and said guide member for tensioning the thread entering said rolls, the improvement which comprises a guide engageable with the traveling thread beyond said guide member, a roller mounted to turn about a fixed axis laterally spaced transaxially from said guide and presenting an external friction surface, said thread extending from said guide member to said guide and reversely around an arc thereof, then to said roller surface and around the latter and in contact with such surface for substantially more than a full revolution, and finally to said rolls, and means continuously exerting on said roller a torque resisting turning of the roller whereby the thread approaching said rolls during turning of the roller is maintained under substantially constant tension determined by the magnitude of said torque.

2. Thread tension regulating mechanism as defined in claim 1 in which said thread after leaving said roller is again led to said guide and reversely around the same and then again wrapped around the surface of said roller in the same direction through more than a revolution whereby to correspondingly increase the tension developed in the thread under said torque as applied to said roller.

3. Thread tensioning mechanism as defined in claim 1 in which the magnitude of said resisting torque is determined by the degree of energization of a magnetic windmg.

4. Thread tensioning mechanism as defined in claim 1 including an electrically conductive rotor rotatable with said roller and an electromagnet with poles disposed adjacent but out of engagement with said rotor, and a winding adapted when energized to cause the induction of eddy currents in said rotor during turning thereof with the advance of the thread against the eddy current drag thus produced.

5. Thread tension regulating mechanism as defined in claim 2 in which the thread after the second wrapping around said roller is led around a third guide surface and then to said rolls.

6. Thread tension regulating mechanism as defined in claim 2 in which the second length of said thread extending from, said guide to said roller is stretched to a greater degree than the first thread length extending from the guide to the roller.

7. Thread tension regulating mechanism as defined in claim 5 in which the first, second and third guides are the bottoms of notches in a member extending along said roller.

8. Thread tension regulating mechanism as defined in claim 5 in which the first, second and third guides are the bottoms of annular grooves spaced along a roll mounted alongside said roller to turn about an axis parallel thereto.

9. Thread tensioning mechanism as defined in claim 1 in which said guide member engages said thread at a point between said thread mass and said guide and exerts thereon a friction force of sufiicient magnitude to prevent the propagation beyond the guide of the slack which may develop from time to time between the package and guide during the unwinding.

10. Thread tensioning mechanism as defined in claim 6 in which the guide member comprises a brush having resiliently flexible bristles projecting across the path of travel of the thread to said guide.

11. In mechanism for handling a stretchable thread having a guide member across which the thread is led from a supply package, power driven rolls engageable with the unwound thread at a point beyond and spaced from said guide member and exerting a continuous pull for continuously unwinding thread from the package, and mechanism engageable with the thread between said rolls and said guide member for tensioning the thread entering said rolls, the improvement which comprises a roller mounted to turn about a fixed axis extending transversely of the traveling thread and presenting an external surface engageable with the thread, a guide spaced laterally from said roller and having a plurality of separate guide surfaces spaced along the roller, said thread extending back and forth between said roller and said guide around said guide surfaces and around said roller surface through more than a revolution and means continuously 7 8 exerting on said roller a torque resisting turning of the 2,972,245 2/1961 York et a1 242-155 X roller whereby the thread in traveling to said rolls is main- 3,026,063 3/ 1962 Seidl. tained under substantially constant tension. 3,092,953 6/1963 Blackstock 5712 X 12. Thread tensioning mechanism as defined in claim 3,113,746 12/ 1963 Steen. 11 in which the surface of said roller is cylindrical. I 5 3,172,186 3/1965 Rodenacker et a1.

3,259,336 7/ 1966 Hibbard. R f r Cited 3,323,302 6/1967 Blackstock.

UNITED STATES PATENTS STANLEY N. GILREATH, Primary Examiner 2,266,632 12/1941 Frey 242---155 2,306,660 12/1942 Gift 242 -155 X 10 2,519,882 8/1950 Bullard et a1. 2,705,362 4/1955 Roughsedge. 106, 242155 

